The Saudi security forces raided several mosques in the Eastern parts of the country and arrested a number of people who had volunteered to protect the mosques.

The security forces attacked a number of mosques in al-Qatif region in Eastern Saudi Arabia, Al-Qatif Mobasher news website reported on Tuesday.

It said that after continued failures of the Saudi forces to protect the Arab country's Shiite mosques from the ISIL attacks over the past two weeks tens of volunteer forces have set up popular committees to foil the ISIL's plots, but some of them have now been detained by the Al-Saud security troops.

Three Shiite mosques in the Eastern province have been targeted by terrorist bomb attacks in the last two weeks.

The website reported that this was the third attack on the Shiites in the past few months, describing it as a repercussion of the war on Yemen and increased divisive remarks by the Saudi clerics against the Shiites.

Prince Mohammed bin Salman plays the main role in the war against Yemen, the website said, adding that the May 22 attack was carried out at the order of the Saudi deputy crown prince to prevent any Shiite movement and possible protests.

At least 21 people lost their lives and 97 others sustained injuries in the bomb attack carried out by the Takfiri ISIL terrorist group.

The figures were announced by Saudi Health Minister Khalid al-Faleh following the attack, which took place at Imam Ali (PBUH) Mosque in the village of al-Qadeeh, located in the oil-rich kingdom’s Qatif district and more than 420 kilometers (260 miles) East of the capital, Riyadh.

A bomber reportedly blew himself up in the mosque as more than 150 people had gathered for Friday prayers.

Later in the day, the Takfiri ISIL terrorist group claimed responsibility for the attack.

Following the bombing, a large number of people took to the streets in Qatif to denounce the terrorist attack. The protesters also chanted slogans to show their anger at Saudi officials over the deadly blast.